Invasive electrical stimulation systems have proven therapeutic in a variety of diseases and disorders. For example, implantable stimulation systems can be implanted in the spinal cord to treat chronic pain syndromes and in the brain to treat refractory chronic pain syndromes, movement disorders, and epilepsy. Peripheral nerve stimulation systems may be used to treat chronic pain syndrome and incontinence. In some cases, paralyzed extremities in spinal cord injury patients may be treated using functional electrical stimulation. Moreover, electrical stimulation systems can be implanted subcutaneously to stimulate subcutaneous tissue including subcutaneous nerves such as the occipital nerve.
In general, a stimulator includes a control module (with a pulse generator), one or more leads, and an array of stimulator electrodes mounted on the lead body. The stimulator electrodes are placed in contact with or near the nerves, muscles, or other tissue to be stimulated. The pulse generator in the control module generates electrical pulses that are delivered through the electrodes to body tissue.
To provide effective stimulation, the electrodes should face the desired body part or tissue to be stimulated. For example, in spinal cord stimulation (SCS), the neurosurgeons should know the orientation of the distal end of the lead supporting the stimulating array of the lead. During deployment, however, the lead may twist or turn such that it may not be deployed in the desired orientation.
In at least some instances, linear spinal cord stimulation (SCS) leads are implanted into the epidural space via an epidural needle. A lead that is incorrectly placed may result in ineffective stimulation. Subsequent surgery may be necessary to re-implant the stimulation system in the desired position.